Computer Graphics Metafile (CGM) is free, platform-independent, international standard metafile format for storing and exchanging vector graphics (2D), raster graphics, and text. CGM uses an object-oriented approach and many function provisions for image production. CGM uses these object-oriented characteristics for remolding graphical elements to render an image. A metafile contains necessary information that defines other files. In CGM, a text-based source file contains all graphical elements that can be later compiled into a binary file.
A file with PPT extension represents PowerPoint file that consists of a collection of slides for displaying as SlideShow. It specifies the Binary File Format used by Microsoft PowerPoint 97-2003. A PPT file can contain several different types of information such as text, bulleted points, images, multimedia and other embedded OLE objects. Microsoft came up with newer file format for PowerPoint, known as PPTX, from 2007 onwards that is based on Office OpenXML and is different from this binary file format.
You can also convert CGM into many other file formats. Please see the complete list below.